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WiFi Client Slow!


ckmcdonald

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I'm using Retrospect Pro v7.7.62 on a 64-bit Win7 Dell desktop PC.

I backup to an external USB3 drive tethered to this desktop.

I also backup a laptop as a remote client.  It is also a 64-bit Win7 Dell machine.

The laptop is only WiFi connected (11g).

 

The backup performance locally on my desktop is acceptable (~1.3 GB/min), but the performance over the WiFi for the laptop backups is coma-inducingly slow.  I have a backup running as I type - Retrospect is reporting a typical performance of 104.8 MB/Min, or 1.75 MB/sec.  The performance of the WiFi on this laptop is as expected for a 54 mb 802.11g link for all other uses.  The laptop is idle and the WiFi band is also pretty much idle besides the backup session.  This isn't a one-time occurrence, it's this slow all the time - it's been months performing like this.

 

I've just been living with it but the size of my backups are growing and the nightly jobs are getting excessively long.

 

Is this a known problem? 

Is it a configuration issue?

Can it be fixed?

 

Thanks

 

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Thanks Lennart and Scillonian.  Studying 11g a little closer I see that you are indeed right.  I had it in my head somehow that 11g was faster than that.  It's pretty depressing living with something so slow I thought it was broken and then find out it's doing as well as can be expected.  :(

 

Wired is problably not going to be an option for me.  11n? 

What can I expect using 11n?

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"The always excellent BareFeats evaluated the Apple AirPort Extreme 802.11n base station and found it to be "3.8 times faster than the 802.11g setup" in real-world tests. The always superb MacInTouch also reviewed the same product and found it to be substantially faster as well but also discovered a number of caveats and limitations that may effect some users."

http://www.everymac.com/systems/apple/apple-tv/apple-tv-faq/what-is-802.11n-differences-between-802.11n-802.11a-802.11b-802.11g.html

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Wired is problably not going to be an option for me.  11n? 

 

If you are going for 802.11n then get an adapter and access point that supports the 5GHz band. Also worth considering may be the new 802.11ac.

 

Personally I avoid WiFi unless I absolutely have to use it.

 

What can I expect using 11n?

 

My personal experience of 802.11n in the 2.4GHz band is of very little performance improvement over 802.11g. A laptop I have that will backup over WiFi occasionally sees a performance of 78-85 MB/minute.

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Started looking into upgrading to 11n.  Discovered (wasn't surprised) that my wireless router supports 11n.  Checked my laptop and discovered (to my surprise) that it too supports 11n.  Why then only a 54mb connection I wondered - it's 30' from the router.  Looking closer I noted two problems,... 11n was disabled on my laptop and the wireless bandwidth of my router was set to 20MHz, not 40Mhz.  I enabled 11n on the laptop and 40MHz bandwidth on the router and the connection rate jumped up to 130mb.

 

The data rate to our iPhones and iPad are also significantly higher now - as they are all 11n.

 

The router is 5GHz capable, but when I turned this on, all our Apple devices lost connection.  I'm guessing they don't support 5GHz?

 

Tonight I'll see how Retrospect does backing up the laptop with 11n enabled.

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Started looking into upgrading to 11n.  Discovered (wasn't surprised) that my wireless router supports 11n.  Checked my laptop and discovered (to my surprise) that it too supports 11n.  Why then only a 54mb connection I wondered - it's 30' from the router.  Looking closer I noted two problems,... 11n was disabled on my laptop and the wireless bandwidth of my router was set to 20MHz, not 40Mhz.  I enabled 11n on the laptop and 40MHz bandwidth on the router and the connection rate jumped up to 130mb.

 

And WiFi is supposed to be easier to setup than wired — if you believe the marketing hype!

 

The router is 5GHz capable, but when I turned this on, all our Apple devices lost connection.  I'm guessing they don't support 5GHz?

The WiFi access point on any good router should be able to run 2.4GHz and 5GHz simultaneously. To work properly the 5GHz band has to have a different SSID to the 2.4GHz band. Devices that only support 2.4GHz will continue to work as normal but devices that support 5GHz will see an additional WiFi network that you will need to connect to using the appropriate credentials to use. To get a device to use the 5GHz network only it may be necessary to remove the connection credentials for the 2.4GHz network.

 

I know the iPad 4TH Generation supports the 5GHz band.

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Last nights' backup run 2-3x slower using 11n. 

 

If I pull up a Status box on the laptop's WiFi connection it reports a pretty solid 54mb for 11g mode but does drop to as low as 36mb at times, but is mostly sitting solid at 54mb.  When I enable 11n it jumps up to 130mb but fluctuates down as low as 65mb.  It reports 130mb about 60% of the time.  (assuming these reported numbers really mean anything)

 

I benchmarked the transfer rate differences between 11g and 11n by copying a large file between the desktop and the laptop (via windows drag-n-drop) - while having all other wireless devices in the house turned off (I did discover my wife doesn't like it when I turn her phone off! :)).    I see the same thing, 11n is 2-3x slower.  I rebooted all devices.  Same result.  All the above mentioned results were with the laptop 6 open-air feet from my wireless router, except the Retrospect nightly backup - which was 30' away.  The 6' - 30' distance change didn't seem to make any difference.  The laptop was otherwise idle.

 

I changed the WiFi channel twice - no difference.

 

11g file transfer rate was about 1.8MB/s

11n file transfer rate was about 650KB/s

 

Anyone have any idea why 11n is slower, even though it's reportedly connecting at a higher bitrate?

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Anyone have any idea why 11n is slower, even though it's reportedly connecting at a higher bitrate?

 

Interference of some kind would be my best guess. There are many other wireless devices that use the 2.4GHz band such as DECT phones, wireless baby monitors and Bluetooth. Neighboring WiFi networks can also cause problems — if the laptop, iPad or iPhone can see them then they have the potential to cause problems.

 

Have you checked the firmware in the router is the latest and the WiFi NIC drivers the latest?

 

By any chance do you have any USB3 devices near the laptop or the router? There is some evidence that some USB3 devices and/or cables can cause WiFi interference. See this white paper from Intel for more details:

 

http://www.intel.com/content/www/us/en/io/universal-serial-bus/usb3-frequency-interference-paper.html

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  • 2 weeks later...

Thought I'd post a conclusion here.  I disabled all wireless devices in my house, cordless phones, bluetooth devices, etc.  The results were the same, 11n is slower than 11g by 2-3x.  There are 2-3 other wireless networks visible (weakly) to my laptop (my apple devices can't see them).  These belong to my neighbors, the closest of which is 272' away.  That seems like a long ways away to be causing much interference but if the problem is 11n interference it must be due to these nearby networks.

 

I configured my laptop back to 11g and am living with the performance of 11g.

I sure would like to get the 3x improvement in performance that 11n suggests it could offer.

 

Thanks again for the help!

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